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A NOVEL INTEGRATED POWER QUALITY CONTROLLER FOR MICROGRID ABSTRACT: A novel variable reactor based on magnetic flux control is proposed in this paper. The system configuration of the novel variable reactor is presented, while its operational principle and dynamic performance are analyzed. Based on the developed variable reactor, a novel integrated power quality controller (IPQC) suitable for microgrid is proposed, which can cater for the peculiar requirements of microgrid power quality, such as the harmonic high penetration, frequent voltage fluctuation and over current phenomenon, and bidirectional power flow and small capacity. For the fundamental, the equivalent impedance of the primary winding is a variable reactor or capacitor. For the nth-order harmonic, the equivalent impedance is very high impedance and acts as a “harmonic isolator.” The system control strategy is also analyzed in detail. A set of three-phase IPQC has been constructed. The experimental test results verify the validity of the novel variable reactor and the IPQC. INTRODUCTION: Distributed power generation has been emerged as a promising option to meet the growing customer needs for electric power with an emphasis on reliability and environmentally friendly renewable energy. In this context, in order to maximize the operational efficiency of the distributed energy resources (DERs) and take full advantage of distributed power generation, as an effective means of integrating DERs into the traditional power grid, microgrid is presented, which can enhance the local customer power supply reliability and system performance, reduce the impact on large power grid, and minimize the system losses. Microgrid has good environmental and economical benefits and has attracted more and more attentions of power researchers. However, the power quality problem of microgrid is much more serious than that of the traditional grid because of the intermittency and randomness of DERs, the high penetration between conventional grid and microgrid, the diversity of DERs, load, energy conversion unit, storage, and operating state. Microgrid power quality has the following unique features compared with the conventional power grid So far, relevant research studies on microgrid power quality con trollers can be sorted into two types: unifunctional controllers and multifunctional controllers. Unifunctional power quality controllers aim at a specific power quality issue in microgrid. Harmonic mitigation is mainly investigated in . Power flow control of microgrid is mostly analyzed . Voltage fluctuation is primarily concerned in . The overvoltage and over current issue is the main concern. Multifunctional power quality controllers generally combine the power quality controller with the grid interfacing converter through special control scheme or topology . However, these multifunctional power quality controllers do not take into account all of the aforementioned features of microgrid. To date, there is less research on integrated power quality controller (IPQC) particularly suitable for microgrid with the aforementioned features. In addition, the microgrid capacity is comparatively small, and it is not cost effective to install various types of power quality controller. EXISTING SYSTEM: This method employs an integrator with reset as its core component to control the pulse width of an ac–dc converter so that its current draw is precisely opposite to the reactive and harmonic current draw of the nonlinear loads. In contrast to all previously proposed methods, there is no need to generate a current reference for the control of the converter current, thus no need to sense the ac line voltage, the APF current, and the nonlinear load current. Only one current sensor and one voltage sensor (resister divider) are used to sense the ac main current and the voltage across the dc capacitor. The control method features constant switching frequency operation, minimum reactive and harmonic current generation, and simple analog circuitry. It provides a low cost and high performance solution for power quality control. Steadystate and dynamic analysis is performed that leads to the remedy of the dc offset related to peak current sensing and extension of the stability region. PROPOSED SYSTEM: The novel IPQC can be installed in series and parallel in microgrid or point of common coupling (PCC). For simplicity, the IPQC is installed in PCC. The three-phase detailed system configuration of the IPQC with transformer and inverter. Us and Ls represent the source voltage and impedance of conventional power supply, respectively. The passive filters, which have the function of absorbing the harmonics, are shunted in both sides. The primary winding of a transformer is inserted in series between the conventional power utility and the microgrid, whereas the secondary winding is connected with a voltage-source PWM converter. Ud is the voltage of the dc side of the inverter. The microgrid contains a harmonic load, a photovoltaic cell system, a battery storage system, and a normal load. ADVANTAGES: Limiting the fault current. Compensating the voltage fluctuation BLOCK DIAGRAM: Passive filters Load Non linear Load Input DC supply Voltage source inverter Filter Voltage source inverter Input source 1 12 V DC 3 phase driver circuit Filter 5 V DC BUFFER circuit Voltage source inverter Input source 2 PIC controller circuit TOOLS AND SOFTWARE USED: MPLAB – microcontroller programming. ORCAD – circuit layout. MATLAB/Simulink – Simulation CONCLUSION: This paper has presented a novel variable reactor based on the magnetic flux control. A transformer with air gap is selected, and the primary winding current of the transformer is detected. A voltage-sourced inverter is applied to follow the primary current to produce another current, which is injected to the secondary. When the injected current is adjusted, the equivalent impedance of the primary winding of the transformer will change continuously. The variable reactor features hardly producing harmonics, simple control scenario, and with consecutive adjustable impedance. The ramp comparison current control with PI controller, which is suitable for DSP microcontroller, is chosen as control current. The optimum PI controller parameters choosing criteria are given in this paper. When the injected current varies suddenly, the novel variable reactor has excellent dynamic characteristic REFERENCES: [1] B. Lasse ter, “Microgrids [distributed power generation],” in Proc. IEEE Power Eng. Soc. Winter Meet., 2001, vol. 1, pp. 146–149. [2] C. Marnay, F. J. Robio, and A. S. Siddiqui, “Shape of the microgrid,” in Proc. IEEE Power Eng. Soc. Winter Meet., 2001, vol. 1, pp. 150–153. [3] R. H. Lasseter et al., Integration of Distributed Energy Resources: The CERTS Microgrid Concept. Berkeley, CA, USA: Consortium for Electric Reliability Technology Solutions, 2002.